Some engines include a variable valve train module which controls valve lift through hydraulic operation. This module can include a block positioned on one or more cylinder heads of an engine. The block can include various spaces for components and cavities for hydraulic fluid which together control valve timing and lift. For example, the block may include a pump which pressurizes a cavity connected to a valve actuator, providing valve lift event control in a manner which benefits engine efficiency (e.g., through variable valve actuation depending on the situation).
The components of the variable valve train module, such as the pump and a brake, are positioned in the block and on the engine. There is often very little space in the block to accommodate the various components and any positioning tools that may be needed. Some components, such as the pump, may have sub-components which currently must be assembled on the block, because a pre-assembled version may be too large to fit into the limited space. This complicates and slows the assembly process or requires a more complicated block design.
The present disclosure is directed to improving the assembly of a variable valve train system by providing a two-piece block design which more conveniently accommodates the components of the system.